Ground effect machines with flexible jet nozzle systems



Nov. 9, 1965 A. w. PRICKETT 3,216,519

GROUND EFFECT MACHINES WITH FLEXIBLE JET NOZZLE SYSTEMS Filed April 2, 1962 2 Sheets-Sheet 1 INVENTOR ALEXANDER W, PRICKETT ATTORNEYS Nov. 9, 1965 A. w. PRICKETT 3,216,519

GROUND EFFECT MACHINES WITH FLEXIBLE JET NOZZLE SYSTEMS Filed April 2, 1962 2 Sheets-Sheet 2 INVENTOR ALEXANDER W. PRlCKETT BY 0 3mg Da /m ATTORNEYS United States Patent 3,216,519 GROUND EFFECT MACHINES WlTH FLEXIBLE JET NOZZLE SYSTEMS Alexander Walpole Prickett, isle of Wight, England, as-

signor to Westland Aircraft Limited, Yeovil, Somerset, England Filed Apr. 2, 1962, Ser. No. 134,482 11 Claims. (Cl. 180-7) This invention relates to ground-effect vehicles and to the provision of flexible barriers for retarding the dissipation of the pressurised ground-effect air cushion, as described in co-pending application No. 181,758 of March 22, 1962 assigned to the assignee of the instant application.

The use of flexible material in constructing the lower parts of the main and other pressure air ducts of groundetfect vehicles is highly desirable, so that the base of the vehicle is less vulnerable to damage, whilst the vehicle can be operated at a lesser height when circumstances are favorable with a consequent saving of power.

When flat flexible sheets of material are used to construct the barrier, forming also the lower parts of the ducts and jet nozzles therefor, as described in the above-mentioned co-pending application, the construction is complicated because it is necessary to support the flexible barrier and/ or jet nozzle against deformation caused by the duct pressure.

Our object in this invention is to provide an improved construction, of the flexible arrangements described, which whilst being self-supporting against the duct pressure is nevertheless extremely flexible and permits easy replacement of any part in the event of local damage.

According to the present invention, a ground-effect vehicle is provided with a flexible jet nozzle system through which air under pressure is discharged downwardly to build up, maintain, and/ or vary the air pressure of the ground-effect air cushion or portions thereof, the system forming also a flexible barrier or barriers to the dissipation of pressurised air constituting the groundeffect air cushion or portions thereof associated with the barriers, and being composed of an assembly of openended flexible tubular components positioned in side-byside relationship to depend downwardly from the rigid base structure of the vehicle. Such a construction can be used both in forming the annular jet nozzle system of peripheral jet type ground-eflect vehicles, and also to form downward extensions and jet nozzles for stabilising or other air-pressure feed ducts. The construction pro- Q vides maximum flexibility when surface obstructions or waves me struck, but at the same time it is self-supporting against the deformatory influence of the duct pressures. The flexible tubular components may incorporate several bores, or they may take the form of a simple tube. In the latter case they are preferably circular or near-circular in cross-section, and are thus capable of retaining their form under the duct pressure. In this way, their walls are subjected in the main to tensile stress only, and the thickness of the walls can be kept at a minimum, so providing the best possible flexibility. Naturally, either single tubes or tubular components having several tube bores, that is to say two or more, may be used either separately or in combination to build up a complete assembly, as considered most suited to their location on the vehicle relatively to the fore and aft parts.

Suitable materials from which such assemblies may be fabricated include rubber, rubber fabric, woven material, synthetic fabric, or plastic sheet such as nylon, Terylene, neoprene or duothene.

Advantageously, each tubular component can be adapted for separate connection to the jet ducts of the "Ice rigid structure of the vehicle. Then, each tubular member is individually flexed when an obstruction is met, thus causing minimum distortion of the flexible assembly as a whole. Any tubes which are damaged can be replaced easily.

Although each tubular component may not be physically connected to the adjacent tubular components in the assembly, a fluid-tight seal between adjacent components, when the assembly is not deflected during striking an obstacle, can be achieved by the abutment of the respective walls of adjacent flexible tubular components which are pressed together in consequence of inflation by the pressure of the air jet passing through them. Thus it will be understood that in constructions utilising flexible tubular components having two or more tubular bores, the components when deflated may take the form of a series of flaps which, when the bores are inflated,are pressed into end contact to form the fluid-tight seals between them.

In order to provide a component of thrust assisting the forward propulsion of the vehicle, the assembly or parts thereof may have a rearward rake relatively to the forward part of the vehicle.

Assembly of the tubular components to the air ducts formed by the rigid structure of the vehicle can be made advantageously by fitting them to a transition manifold which is in turn fitted to the rigid structure. Conveniently, this manifold can be composed of an assembly of rigid junction pieces formed with hollow tubular parts which fit into the bore or bores of the flexible tubular components with which they are associated. Each junction piece is then preferably basically square or rectangular at the top, to fit both the rigid part of the air duct and also mate with adjacent junction pieces of the assembly to make fluid-tight joints. The shape of each junction-piece then changes gradually to form one or a series of parts of circular or near-circular cross-section, corresponding to the cross-sectional shape of the bore or bores of the tubular component with which it is associated. This permits fitting of the flexible tubular components by means of simple clips or clamps to facilitate removal and replacement.

To control the collapsed or deformed shape of the flexible assembly when the vehicle is resting upon the ground, or during wave impact, the nozzle ends of the tubular components may be attached to the lower edge of a flexible membrane, the other edge of which is secured to the base structure of the vehicle a predetermined distance within the periphery.

The flexible tubular components can be advantageously provided with a degree of taper or with nozzle-shaped ends, to increase the wall tension and thus assist resistance to the outwardly-directed pressure of the ground-effect air cushion built up between the base of the vehicle and the surface over which it is operating. This in turn increases the efficiency with which they form a flexible barrier to retard dissipation of the air cushion pressure.

The invention will now be described in more detail, by way of example only, as applied to constructions in which the flexible tubular components take the form of an assembly of simple tubes.

Referring to the drawings:

FIGURE 1 is a diagrammatic plan view of a groundeflect vehicle;

FIGURE 2 is a diagram of the ground-effect vehicle, sectioned along the line 11-11 of FIGURE 1;

FIGURE 3 is a section on the line III-III of FIG- URE 2;

FIGURE 4 is an enlarged drawing of the part shown encircled in FIGURE 2;

FIGURE is a section on the line VV of FIGURE 4;

FIGURE 6 is a section on the line VIVI of FIG- URE 4;

FIGURE 7 is a scrap view showing a modification, and;

FIGURE 8 is a scrap view showing another modification.

In carrying the invention into effect according to one convenient form which is by way of example only, FIG- URES 1 and 2 represent a plan and sectional view of a ground-effect vehicle generally indicated at 1 having a pilots cabin 9, a centrally disposed air intake 2 housing a fan 3 driven by an engine 4 The outer casing 5 and the inner casing 6 radiate outwards from said air intake 2 and together form the outer and inner walls respectively of an annular duct 19 which terminates in a peripheral jet 7 extending around the base of said vehicle 1.

Referring to FIGURES 2, 3 and 4 it will be seen that the peripheral jet '7 which in this example is inclined inwards towards the centre of the vehicle 1 is extended to the required degree by a plurality of flexible tubes 11 made from rubber, rubberised fabric, woven fabric, plastic, or any like material, natural or synthetic, having either parallel walls or walls tapering towards their lower end which terminate in a suitably shaped nozzle 12. The flexible tubes are installed in a manner such that said tubes are in tangential contact with each other and may be connected by any convenient means to the walls of said peripheral jet 7. However, for the purpose of illustrating the invention, sleeves or transition pieces 10 are used, said sleeves being formed so that they have a substantially square or rectangular section at their upper end to conform with the shape of said peripheral jet 7, gradually transforming to a substantially round section at their lower end, a shape adapted to receive the flexible tubes 11.

Referring to FIGURE 5 it will be seen that each sleeve or transition piece 10 abuts the adjacent sleeve 10 to form a face joint and is located on the inside of the peripheral jet 7 by any convenient means such as screws, nuts and bolts, or spring catch means, in such a manner as to be a good fit within the jet 7 in that the joints are substantially air tight. Likewise the flexible tubes 11 could be convenienly connected to the outside lower end of said sleeve 16 by a screw clip means 18, or any like arrangement and this connection should also be substantially air tight.

Referring to FIGURES 4 and 6 it will be seen that connecting the lower end of the flexible tube 11 to the main body of the vehicle 8 by way of retaining strap 14 is a flexible curtain or membrane 13, which constrains said flexible tube 11 inwardly against an air pressure force from the air cushion 17 and a nozzle reaction force at 12. However, it should be clearly understood that the specific flexible curtain 13 is not an essential feature of the invention as the tubes 11 can be made to be self-supporting. The flexible curtain or membrane 13 is also made from rubber, rubberised fabric or like material and has suitably placed air vent holes 15 and water drain holes 16 which may also be provided with simple flap valves (not shown) made of rubber or similar material, in order to prevent a build up of water pressure in the cavity formed by said flexible tubes 11, said flexible curtain 13 and the main body of the vehicle 8. As an alternative, in the stern or trailing edge position elastic or spring assisted tension members may be used in place of said curtain 13.

It will also be apparent to those skilled in the art that in carrying the invention into effect according to a modified form, the aforementioned sleeves or transition pieces 10, may if so desired, be manufactured in such a manner as to form short sections having two or more integral sleeves; likewise the aforementioned flexible tubes 11 could be manufactured in a similar manner, and adapted so that the two said parts 16 and 11 correspond and could be fitted in groups for convenience or case of maintenance.

In another modified form of the invention each sleeve or transition piece 10 could be made to accommodate twin flexible tubes joined at their point of contact and having the sectional form of a figure eight, said tubes being installed in the peripheral jet in such a manner as to present an inner and outer bank.

FIGURE 7 shows a further modified form of the invention in which sleeves or transition pieces 10 together with the flexible tubes 11 are mounted in the vertical plane both in elevation and end view, whilst FIGURE 8 shows yet another modified form of the invention in which said sleeves 10 and said tubes 11 are inclined at an angle towards the stern of the vehicle, and could also be inclined inwards towards the centre of said vehicle.

In operation of the invention it will be clear from FIGURES 1, 2, 3 and 4 that if the engine 4 of the groundeifect vehicle 1 is driving the fan 3, air will be drawn into the intake 2 and compressed in the annular duct 19 formed between the outer casing 5 and the inner casing 6, and will be forced along said duct 19 and discharged through the flexible tubes 11 attached to the peripheral jet 7, at the lowest extremity of said duct 19, by way of sleeves of transition pieces 10. Hence a jet of high pressure air is emitted from the nozzle 12 which serves the dual purpose of supplying air to form what is now commonly called an air cushion 17 beneath the vehicle 1 for the purpose of lifting and motivating same. The jet of high pressure air also forms a fluid barrier which substantially reduces the rate of dissipation of said air cushion 17 from around the periphery of said vehicle 1.

As hereinbefore described the flexible tubes 11 are so closely installed within the peripheral jet 7 as to be in tangential contact with each other and when compressed air is passed through said tubes 11 they will inflate in the manner of a fabric hose and so increase their contact pressure with the adjacent tube Thus the peripheral jet 7 has been physically and flexibly extended so as to form an unbroken barrier and the air cushion 17 has little chance of escaping between said tubes 11 unless said tubes are temporarily displaced. The flexible tubes 11 may be prevented from being forced outwards by cushion pressure and by nozzle reaction, by way of the flexible curtain or membrane 13 which is connected to said tubes 11 by retaining straps 14 to the underside of the vehicle 8; although this is not an essential feature of the invention, as with certain geometrical proportions and nozzle shapings it would be possible to make said tubes 11 self-supporting.

When travelling in a forward direction at a low clearance height, should the flexible underpart of the vehicle 1 strike a wave or project object a tube or group of tubes 11 will be temporarily deflected rearwards, or sideways thus allowing the main body of the vehicle to pass undamaged Said vehicle having cleared said wave or object, said tube or tubes 11 will return to their normal substantially vertical position assisted by cushion pressure 17 and by reaction from the nozzles 12, being retained in said normal position by way of flexible curtain 13 or by air pressure acting within the tubes 11. In the case of the flexible tubes 11 disposed across the stern or trailing edge of said vehicle 1 there is a tendency for said tube or tubes 11 to buckle in a rearward direction, and elastic or spring assisted tension members may be used in these positions to return said stern or trailing edge tubes 11 to their normal position, which would entail movement against the cushion pressure 17 Flexible tubes disposed in such a position are not assisted by cushion pressure 17 and reaction from the nozzles 12 as is the case with tubes in other positions.

In order to facilitate the collapse of the flexible curtain 13 when the vehicle 1 alights on a hard surface, and also to prevent a build up of water pressure within the cavity formed by the tubes 11, curtain 13 and under side of vehicle 8, on impact with a wave air vent holes and water drain holes 16 are provided in any suitable positions around said flexible curtain 13. Said drain holes 16 may be fitted with simple flap valves (not shown) opening inwardly, i.e towards the centre of the vehicle.

In operation of a modified form of the invention as illustrated in FIGURE 8 a swept back arrangement of the flexible tubes 11 wiil provide thrust for the vehicle 1 for propulsion purposes It will be apparent from the foregoing description that should the vehicle be moving crabwise under the influence of extraneous forces, or have need to manoeuvre in any other direction than forwards, it will not substantially aflfect the operation of the invention.

I claim as my invention:

1. In a ground eflf'ect vehicle, a base structure, an annular jet system for generating a pressurized air cushion under at least a portion of said base structure, said jet system comprising a substantially continuous discharge passage extending around at least a portion of said base structure and being directed downwardly from said base structure, a continuously adjacent series of flexible tubular components connected to said discharge passage in side by side relationship to depend downwardly from the base of the vehicle, at least some of said tubular components being free to flex independently of adjacent tubular components, whereby pressurized air issuing from the adjacent lower ends of said tubular components will function to create and maintain a pressurized air cushion under the portion of the base around which they are arranged, and whereby said adjacent flexible tubular components act as a barrier to dissipation of the air cushion but flex to permit said vehicle to pass over obstacles.

2. Apparatus as set forth in claim 1 wherein groups of two or more of said flexible tubular components are interconnected along their abutting sides so as to flex together.

3. Apparatus as set forth in claim 1 in which at least some of the flexible tubular components have a rearward rake relative to the longitudinal axis of the vehicle to provide an element of forward thrust to the vehicle.

4. Apparatus as set forth in claim 1 wherein said flexible tubular components are of substantially circular cross section.

5. Apparatus as set forth in claim 1 wherein said flexible tubular components are attached at their upper ends to junction members, said junction members being of a shape corresponding to the cross sectional shape of said discharge passage so as to be insertable in said discharge passage.

6. Apparatus as set forth in claim 5 wherein a single flexible tubular component is attached to each junction member, and each junction member is in substantially abutting engagement with adjacent junction members.

7. Apparatus as set forth in claim 5 wherein a plurality of junction members are connected in side by side engagement to form a manifold member for a plurality of said flexible tubular components.

8. Apparatus as set forth in claim 5 wherein at least some of said junction members are angled in their lower portions so as to impart a rearward rake to their connected flexible tubular components relative to the longitudinal axis of the vehicle.

9. Apparatus as set forth in claim 1 further comprising flexible means extending between the base structure of said vehicle and the lower ends of at least some of said flexible tubular components so as to at least partially con trol the orientation of said flexible tubular components and to constrain the outward movement thereof.

10. Apparatus as set forth in claim 9 wherein said flexible means comprises a membrane-like member.

131. in a ground effect vehicle, a base structure, an annular jet system for generating a pressurized air cushion under at least a portion of said base structure, said jet system comprising a series of continuously adjacent downwardly directed flexible tubular members extending around at least a portion of said base structure, said flexible tubular members being arranged in side by side relationship and having their adjacent walls in abutting engagement at least when pressurized air is passed through said flexible tubular members at least some of said tubular members being free to flex substantially independently of adjacent tubular members, and means for passing pressurized air through said tubular members to discharge from the adjacent lower ends thereof.

References Cited by the Examiner FOREIGN PATENTS 1,238,499 7/60 France.

860,781 2/61 Great Britain. 137,405 4/61 Russia.

A. HARRY LEVY, Primary Examiner.

PHILIP ARNOLD, Examiner. 

1. IN A GROUND EFFECT VEHICLE, A BASE STRUCTURE, AN ANNULAR JET SYSTEM FOR GENERATING A PRESSURIZED AIR CUSHION UNDER AT LEAST A PORTION OF SAID BASE STRUCTURE, SAID JET SYSTEM COMPRISING A SUBSTANTIALLY CONTINUOUS DISCHARGE PASSAGE EXTENDING AROUND AT LEAST A PORTION OF SAID BASE STRUCTURE AND BEING DIRECTED DOWNWARDLY FROM SAID BASE STRUCTURE, A CONTINUOUSLY ADJACENT SERIES OF FLEXIBLE TUBULAR COMPONENTS CONNECTED TO SAID DISCHARGE PASSAGE IN SIDE BY SAID RELATIONSHIP TO DEPEND DOWNWARDLY FROM THE BASE OF THE VEHICLE, AT LEAST SOME OF SAID TUBULAR COMPONETS BEING FREE TO FLEX INDEPENDENTLY OF ADJACENT TUBULAR COMPONENTS, WHEREBY PRESSURIZED AIR ISSUING FROM THE ADJACENT LOWER ENDS OF SAID TUBULAR COMPONENTS WILL FUNCTION TO CREATE AND MAINTAIN A PRESSURIZED AIR CUSHION UNDER THE PORTION OF THE BASE AROUND WHICH THEY ARE ARRANGED, AND WHEREBY SAID ADJACENT FLEXIBLE TUBULAR COMPONENTS ACT AS A BARRIER TO DISSIPATION OF THE AIR CUSHION BUT FLEX TO PERMIT SAID VEHICLE TO PASS OVER OBSTACLES. 